Pickling agent for copper-beryllium alloys



. solution.

Patented June 2, 1942 BEST f i PICKLING AGENT FOR COPPER-BERYLLIUMALLOYS Henry Kawecki, Temple, Pa., and Wayne E. Martin, Bayside, N. Y.,assignors to The Berylw York, N. Y., a corporalium Corporation, Ne tionof Delaware No Drawing. Application March 28, 1941, Serial No. 385,690

6 Claims.

This invention relates to metallurgy and more particularly to picklingsolutionsfor use in the removal of surface scale and oxides fromcopper-beryllium alloys. In the manufacture of articlescomprised ofcopper-beryllium alloys the cast alloy must be subjected to hot Workingand heat-treatment operations prior to any cold mechanical deformationof the same and prior to such cold mechanical deformation the scale onthe surface of the alloy must be removed. Frequently also the coldworked alloy must be heattreated to anneal the same, resulting insurface discolorations due to oxidation. One of the objects of thepresent invention is to provide an effective pickling agent for theremoval of surface scale and oxides from said alloys. Another object isto provide a pickling solution that is relatively inexpensive, readilycorrosive towards copper and beryllium oxides but substantiallynon-corrosive towards the alloy per se and a solution that is usefulover substantially prolonged time intervals towards successive batchesof said alloy. Still another object is to facilitate the surfacecleaning of copper-beryllium alloys. Other objects and advantages willbe apparent as the invention is more fully hereinafter disclosed.

In accordance ,with these objects, we .have discovered that a causticalkali aqueous solution, particularly .a strong or concentrated causticalkali solution containing from 25 to 50% caus In general we add only asmall amount of sodium agent is deleteriously affected. For mostpickling operations on cold Cu.Be alloys we prefer to maintain thecaustic alkali concentration within the range 40-50%, the sodium ticalkali, such as a 50% (by weight) NaO H,

solutions towards BeO and CuO increases with increase in temperature andwith increase in caustic alkali concentration up to about 50% butdecreases with increase in cupric ions in the We have found that byadding an alkali cyanide to the caustic alkali solution,\ therebyproviding'free cyanide ions in the solution, the cupric salts formed onsolution of CuO in the alkali solution are converted into complexcuprous cyanide compounds and the solution activity of the causticalkali solution thereby is maintained at its maximum at any giventemperature and range of caustic alkali concentration.

The amount of sodium cyanide in the caustic alkali solution may bevaried widely without 'essential departure from the present invention.

cyanide concentration within the range 5-l0%, and the temperature of thesolution within the range 80-l00 C. a

As a modification of the present invention, the pickling solution aboveidentified may be employed as a combined pickling and quenching bath forCu.Be alloys. In the mechanical deformation of Cu.Be alloys, it isfrequently necessary to heat treat the metal to temperatures known inthe art as beta-solutioning temperatures for prolonged time intervals.Following such heat-treatments the metal is cooled rapidly to preservethe solid solution structure formed at the temperature of treatment inorder to condition the metal for cold mechanical deforma tion. Suchheat-treatments are frequently practiced during both hot and coldmechanical deformation and invariably result in considerable -thepreceding heating step.

It is believed apparent from the above description-that the presentinvention may be widely varied without essential departure therefrom andall such modifications and departures are contemplated as may fallwithin the scope of the following claims.

2. A pickling agent for removing scale and metalo'li des from thesurface of copper-beryllium cor? y mi AVAILABLE cow alloys, said agentconsisting of water containing up to 50% (by weight) of a caustic alkaliand up to 10% (by weight) of an alkali cyanide.

3. A pickling agent for removing scale and metal oxides from the surfaceof copper-beryllium alloys,,said agent comprising a caustic soda andsodium cyanide aqueous solution, the concentration of said caustic sodaapproximating 40-50% (by weight) and the concentration of said sodiumcyanide approximating 510% (by weight).

4. The agent of claim 3, heated to temperatures approximating 100 C.

5. The method of removing surface scale and metal oxides fromcopper-beryllium alloys which comprises immersing the same in a picklingbath comprised of an aqueous solution containing from 25-50% causticalkali and sodium cyanide from small but efiective amounts up to about10%.

6. The method of removing surface scale and metal oxides fromcopper-beryllium alloys which comprises immersing the same in a picklingbath s comprised of an aqueous solution of caustic soda and sodiumcyanide heated to elevated temperatures within the range 80100 C.

H. C. KAWECKI. W. E. MARTIN.

